The surge tank is there to maintain a constant flow and pressure to the injectors no matter what the car's doing. It's handy for racing, drifing, autocross, and even off roading. Some aircraft use them. By design, the surge tank is pressurized, and as close to the injector fuel rails as possible. Carb float bowls are unpressurized small surge tanks.
You can place the surge tank almost anywhere. I suppose you could even place it inside the original tank to save space. But it's going to be most efficient placed as close to the injector rail as possible.
http://www.superstreetonline.com/pro...el_surge_tank/
http://msextra.com/doc/ms3/fuel.html
Another use for a surge tank is conversion from carb to EFI - like an old Mustang. The original mechanical pump feeds a surge tank containing a high pressure pump - which then feeds the injector rails.